The present invention relates to a spinning wash nozzle assembly and in particular to a nozzle assembly having a liquid pump brake contained within a rotating spinner housing such that centrifugal forces separate the pumping liquid from air contained within the liquid to ensure that only the liquid is drawn into the pump.
A spinning wash nozzle assembly is known in the prior art from U.S. Pat. No. 5,020,556. This spinning nozzle comprises two main parts: 1) a rotating spinner head and shaft and, 2) a stationary housing providing bearing support for the rotating spinner head and shaft. Water enters the nozzle assembly through a fitting fastened to a support structure. A plurality of nozzles attached to the spinner head provide outlets for the pressurized water. The nozzles are set at an angle relative to the rotational axis of the spinner head such that the reaction forces from the water jets cause the spinner head to rotate about its axis. The rotational speed of the spinner head is controlled by a fixed displacement internal/external gear oil pump acting as a braking device by adjusting pump discharge flow pressure. The braking pump in this prior patent includes an inner gear coupled to the spinner head shaft for rotation therewith and an outer gear fixed to the housing. The housing further contains an oil sump for oil pumped by the braking pump. One problem associated with such a braking pump is the undesirable effect on the pump of air mixed within the oil.
The present invention provides a spinning wash nozzle assembly in which the braking pump as well as the fluid or oil sump for the pump are placed in the rotating spinner head and as opposed to the stationary housing as shown in the above referenced patent. This results in a simpler and a less expensive construction which has a further functional advantage. Due to the centrifugal effect on the rotating oil pump, any air present in the oil separates from the oil. The heavier oil moves radially outward while the lighter air moves radially inward, toward the axis. As a result, only oil is available at the pump inlet such that the oil drawn into the pump is free of air.
The pump is also configured with the inner gear held stationary while the outer gear is rotated. The discharge pressure of the oil pump is controlled by a pressure-regulating valve. The valve is biased either by a spring or by a centrifugally-generated force. In addition, temperature compensation can be provided through a bimetallic spring which produces a spring-force variable in relation to oil temperature.